Solar activity has had minimal impact on climate over the past millennium, new research from the United Kingdom indicates. The findings counter the long-held view that periodic fluctuations in the sun's energy output have led to lengthy periods of warm or cold weather in the past. Looking at climate records from the Northern Hemisphere over the past 1,000 years, the scientists found that greenhouse gases have been the primary drivers of climate change since about 1900. Volcanic activity, which adds particles to the atmosphere that block sunlight, dominated climate patterns until roughly 1800, the study found. "Until now, the influence of the sun on past climate has been poorly understood," said Andrew Schurer of the University of Edinburgh and lead author of the study, which was published in Nature Geoscience. "We hope that our new discoveries will help improve our understanding of how temperatures have changed over the past few centuries, and improve predictions for how they might develop in future."